The following quotes are especially pertinent when dealing with the current debate between “versus populi” and “ad orientem.” I find the first quote from the Holy Father’s The Spirit of the Mass to be especially relevant:
Despite all the variations in practice that have taken place far into the second millenium, one thing has remained clear for the whole of Christendom: praying toward the east is a tradition that goes back to the beginning. – The Spirit of the Liturgy (Ignatius Press, 2000), pg. 75
It is essential for us to realize that since the time of the Apostles, it has been traditional for the Church to pray facing east. The Gregorian Mass is served “ad orientem” as are the liturgies of the Armenians and the various Orthodox churches.
Our Lady of the Angels, pray for us!